Let the TheaterCommander manage front line stance.

This improves the AI behavior by choosing the stances non-randomly:

* Breakthrough will be used if the base is expected to be capturable and
  the coalition outnumbers the enemy by 20%.
* Elimination will be used if the coalition has at least as many units
  as the enemy.
* Defensive will be used if the coalition has at least half as many
  units as the enemy.
* Retreat will be used if the coalition is significantly outnumbers.

This also exposes the option to the player.

game/commander/tasks/packageplanningtask.py

@@ -40,6 +40,9 @@ class PackagePlanningTask(TheaterCommanderTask, Generic[MissionTargetT]):
     def __post_init__(self) -> None:
         self.flights = []
 
+    def preconditions_met(self, state: TheaterState) -> bool:
+        return not state.player or state.ato_automation_enabled
+
     def execute(
         self, mission_planner: CoalitionMissionPlanner, tracer: MultiEventTracer
     ) -> None: